Future Interface in Java

import java.util.concurrent.*;
public class GFG{
    public static void main(String[] args) throws Exception{
        // Create an ExecutorService
        ExecutorService executor
            = Executors.newSingleThreadExecutor();
        // Define a Callable task
        Callable<Integer> task = () ->
        {
            System.out.println("Processing...");
            Thread.sleep(1000);
            return 10 * 5;
        };
        // Submit the task and get a Future object
        Future<Integer> future = executor.submit(task);
        // Check if task is done
        System.out.println("Task completed? "
                           + future.isDone());
        // Retrieve the result
        System.out.println("Result: " + future.get());
        // Check again
        System.out.println("Task completed? "
                           + future.isDone());
        // Shutdown the executor
        executor.shutdown();
    }
}

import java.util.concurrent.*;
public class GFG {
    public static void main(String[] args) throws Exception{
        ExecutorService executor
            = Executors.newSingleThreadExecutor();
        Callable<String> task = () ->
        {
            Thread.sleep(2000);
            return "Task Completed";
        };
        Future<String> future = executor.submit(task);
        // Cancel the task before it finishes
        boolean cancelled = future.cancel(true);
        System.out.println("Task cancelled? " + cancelled);
        executor.shutdown();
    }
}